The present invention relates to a multicell battery composed by connecting a plurality of cells.
Recently, multicell batteries formed by connecting a plurality of cells in series have come to be used widely. A diagram for explaining the method of connecting a conventional multicell battery is shown in FIG. 8. As shown in FIG. 8, one end of a lead tab 115 is preliminarily spot-welded to a first electrode terminal 113 having a convex shape provided at an upper end of a first cell 111. The lead tab 115 is bent at right angle. The other end of the lead tab 115 is then welded to a second electrode terminal 124 having a flat shape positioned on the bottom of a case 122 of a second cell 121. Consequently, the lead tab 115 is folded 90 degrees so that the center line (B) of the second cell 121 connected to the first cell 111 may be aligned with the center line (A) of the first cell 111. In such process, a conventional multicell battery was manufactured.
In the conventional manufacturing method, however, the lead tab 115 must be cut longer than required length. Therefore, depending on the length of the lead tab 115, the internal resistance of the multicell battery increases. Another problem was the high manufacturing cost. The first cell 111 and second cell 121 must be welded through the lead tab 115, and the lead tab 115 connecting the first cell 111 and second cell 121 must be folded 90 degrees, and hence complicated processes were needed, and the productivity was poor.
It is hence a goal of the method of manufacturing a multicell battery of the present invention to decrease the internal resistance of the multicell battery, enhance productivity, and lower the manufacturing cost.